ADALM-Pluto

  • Yes I have seen a Dutch user do that as well, he has a nice signal on the TV repeater. ADALM PLUTO plus one of those small pre-amps as a linear (to get a little more output, like 20mW or so) and a PCB yagi brings him into the repeater that is 40km away.

  • Dear Heiner,


    your tests are very interesting, but how much power can manage this device ? I read a characteristic about 0 dBm, for my needs not enough. Furthermore my idea is to send signal to a converter BU500 at 144 MHz. Unfortunately this device start from 325 Mhz...This drive me to select another solution.


    73 Alex

  • Latency of Adalm-Pluto...


    I think a not negligible problem is the digital processing times plus the latency over the satellite. Since come equal 1500 mS together (RX 600mS - Sat Latency 250mS - TX 600mS). Maybe a problem for FT8?

  • Latency of Adalm-Pluto...


    I think a not negligible problem is the digital processing times plus the latency over the satellite. Since come equal 1500 mS together (RX 600mS - Sat Latency 250mS - TX 600mS). Maybe a problem for FT8?

    For FT8, a delay of 1500 msec is not an issue.

  • As a matter of fact?

    Yes. The worst offsets I have in my FT8 log are -2.6 seconds and +2.5 seconds.

    There's also still some opportunity for latency optimization.

    With clever coding that can be reduced.


    I have a prototype SSB modulator with ~62ms latency working, which is running directly on the PlutoSDR. But I don't think such drastic measures are actually needed for practical usage of FT8.

  • Anyway ...

    Another idea: ADALM-PLUTO has integrated RX and TX, actually the ideal condition to use the device also with suitable software as a VSWR (reflection attenuation) measuring device via a directional coupler.

    Has any of you aoready tried it? Any idea?


    73´s de Robert

  • Hi,


    recently I made some measurements of the drift of the Pluto SDR after TX start. It was quite substantial an IMHO prohibts using it for FT8. Even for CW and SSB it will require the receiving station to constantly tune his receiver which I do not want ...


    Here are some graphs of my measurements:




    The next step is to try to disable the internal 40 MHz reference and supply it from an external GPSDO. Hopefully that will solve the problem.


    Regards


    Matthias


    http://www.dd1us.de

  • Anyway ...

    Another idea: ADALM-PLUTO has integrated RX and TX, actually the ideal condition to use the device also with suitable software as a VSWR (reflection attenuation) measuring device via a directional coupler.

    Has any of you aoready tried it? Any idea?


    73´s de Robert

    Task solved ..

    I´ve now found a solution using MATHLAB to use ADALM-PLUTO as an SDR reflectometer. The result is amazingly good. Comparisons with purchased SHF filter and R&S measurement results are the same.

    Here a plot of my 3-band helix feed, the 13cm part:



    73´s de Robert

  • DD4YR Robert can you share your solution here?

    Of course. I oriented myself on an article on EngineerZone from Analog Devices. The source code for MATHLAB can be used 1:1. fits.

    The measurement takes place in two steps. First, the forward current power is detected from the reflectometer on the frequency spectrum to be scanned. Then, you have to change the reflectometer, in the second step the reflected power is recorded, subtracted and plotted.

    The only drawback: Yo can not measure in real time, since the measurement runs already takes 2 minutes ...


    Items: https://ez.analog.com/universi…r-vector-network-analyser


    btw: I use the 30 days trial version of MATHLAB .. :-)


    73´s de Robert

  • Hi,


    recently I made some measurements of the drift of the Pluto SDR after TX start. It was quite substantial an IMHO prohibts using it for FT8. Even for CW and SSB it will require the receiving station to constantly tune his receiver which I do not want ...

    Remember the ADALM PLUTO is a learning and experimenting device, not necessarily a wise choice to use as the core of an amateur radio station.

    Before you can do that, you need to add external filtering and for such high frequencies maybe a better reference and by that time it could have been wiser to buy a device that is properly constructed for the purpose.

    This does not mean it cannot be a lot of fun to tinker with the PLUTO.

  • Works fine ..

    Saturday i have been done the same test, successfully. I tried also 2400 MHz TX result was the same, good picture obtained. Unfortunately connecting ADALM_PLUTO to BU500 converter, I discovered some issues. The unfilitered signal from ADALM causes burning my amplifier. The accident is caused without connecting any signal in TX. This meaning that when ADALM does'n transmit, has anyway a "grass" of RF, that is so dangerous if you connect ADALM to other devices without filtering. The solution may be filter the band outside 2400 Mhz, and connect to a amplifier after a good filtering. But this do not guarantee that in the 10 MHz spectrum you have a very clean emission....